light passes through transparent objects like water and glass ,where in case of glass the molecules are more tightly packed or concentrated then to it allows light to pass, Why?(yet reflection occurs but why the rest light passes)
It will be good if your read the similar question linked by Rob., it covers transparent materials.
I will start with the fact that light is composed of photons. This is completely clear in the single photon at a time double slit experiments, where the interference pattern is shown to be built up over time by individual photons.
The quantum mechanical problem "photon scattering through two slits" has the solution seen in the last slide , i.e. a probability distribution for where the photon goes.
A photon can impinge on a lattice made up of atoms. Depending on the lattice organization and the available energy states the solution "photon +lattice" goes:
1) photon elastically scattered backwards ( reflection)
2) photon absorbed in available excited states of atoms/molecules/lattice and its energy cascaded down to infrared/heat_photons
3)photon running the gamut as in the double slit experiment and managing to get through interacting elastically and not loosing energy and going through.
No3 is what happens in transparent materials, from water to glass to diamonds and the structure is such that the solution allows the elastic scatter with small deviations which are macroscopically seen as refraction and labeled with an index for each material.
If we ran an experiment one photon at a time as in the double slit, the solution will be the one appropriate for the material under study.
Light is built up by an enormous number of photons, which in synergy build up the beam of light we easily observe. The reason images are retained through transparent materials is that photon-photon interactions are very weak and the beam keeps its geometric coherence, the photons working in step within the beam following the solutions from the given initial conditions.